SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7c3ab320340d45196d81e9f084ad8d9718776806eb26d2214b3977c53f945c4' 
  AND token = 'ADuW9HMq/uBMTTUHGMr0vsQ5tzuEp+1zJfKZrsMazLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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