SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e530e88c78d21c2a18424820bef368d4ad09ba56b003bf389998b688e9dee53' 
  AND token = 'zQl0yMy2Q2Z0+cLFQYTLlzzl7rIdFOF2c0qUdIpW4oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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