SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe8be03dab0be187dc04af17210550759ef82941f3f6025fa1b4baf21bf6e155' 
  AND token = 'F9pVzMcGVVbqu79Y+KA7rKZ9Xu/SK/8pXK11GjfumyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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