SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c147e3de5eb135b68716fa200895c5bd9ee86d1e529a9fa76116ee7434f725aa' 
  AND token = 'c2gHkkH4VVHuwRqvVhCx+Zx5qUMak2Kkr5ZBwCwDQF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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