SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7639a763eb036529da9eca128a2486bf38a5c6e3392bfd16f160e4bc2d6e2da4' 
  AND token = '84UbmMAXrEsL1pQ3JKf9rfeZV/ljkWFuAHfdYSumrTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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