SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c1b3f094215238c50f70f215f735d63d86089b4be2995d66393d443d87c7615' 
  AND token = 'eUjBcF8zlibJpsZr+WAhb31FOjKJ1++4+dQMzQ+ij7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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