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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a7e9d22418606111090749534365c39e1a4bafc5d38fb8dc2899a455fddf77d' 
  AND token = 'gmgBx4A1F4m8xYT/mOx8fiLLixYqYoDaiMTejaexp1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}