SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eabd28d03411750d63821e0d272107a1ad2ea749baada85540908e2519e6f73a' 
  AND token = '1ISV2RTlqnRC8DZUzjIMAz+d7x3+l5jSjffavQxzqD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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