SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e38e49b820b59ca13722d573cc5d62fc8f6e4458e1a5ebcf1fcc6915090d02cc' 
  AND token = 'q9JCbrjmYd5ZTvA41FOP2R1Q+RjacC5lUeNVh0myGYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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