SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398f787b54ae442da242452713225fed369ec74646198879b3e0b6e34cc065f1' 
  AND token = 'JB0jEG5B0d5l0Gxx7q3BtGxuV5mXWXG3kN3zwQliBWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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