SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b0ddac0800989989ee34a4c880441b3f35798b0a4bd94c683556f8bd56bf37e' 
  AND token = '+mLEz1mfcSGWwQAar0Yt+fR0vOc2cETiUmbKyePlmK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}