SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c2b5a365348cdebbb187761cdc6eb86f292973268b43e15e528fd27a625a79a' 
  AND token = 'Fx++UZC6pXMXJcvCLTvO6vpxxmiocoMwSqPd/gIj9Vo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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