SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '294a6f104bd9a1e38e990a794641a8d86e03e6376c3dd5935690d261294de9aa' 
  AND token = 'ZZDktDtVgQKWh48gpqZkhwd8mhjMmySDUwu8/Scui7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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