SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de6cd656676f878dd31b62d69cb9d7394dbae51ab84ca010b541e15cee596e95' 
  AND token = '21wffvH0b5uBDFAQAYBg0lbfTG7zseiTrqqjKK+X3uU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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