SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f71c70893cdcbddac9d808afd19b7da3d200626657c4831c3e29436c8fe7fff8' 
  AND token = 'tW6ekSJtcwvi0wcRtpkIt4UzPHcG7pffT4t4mVY327Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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