SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7908e28940058cd17832c7f88b1744e9da46542914033a4af5a0788a1f9d6251' 
  AND token = 'B0+2kz6VBekxWPb97yWMLgkXZQzEhvwKLLJQzM9hdkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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