SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a236c4769e0e15c51be7e5b45e6c9a1c80de80413281f4d5e1896f031296cb33' 
  AND token = 'pHEfuIn+IkmuN8PK2cHEgfJh4BkrdgkKN4ehTpWglx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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