SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88c5e2f8710de8fe9ba32e62ba50c4cf4252fa9654daf0f0b91dab0bf0122dd2' 
  AND token = '2Fs0jF+rRRjPkI3qTWD04kB0DtD/zOa5v5/nIbUPQaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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