SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd99dcd5c21f5d19410441c2fcb1828737399664e7a385551d1f76db29e36785b' 
  AND token = 'uldV+FBxcwipkLgGAgrAZ/GIdRqGMxswDhKGRjFUE1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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