SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74adc8581ba1c4ece7eae15537cdc3aa23683a1a54018f8409157631b7a3fe31' 
  AND token = 'vARBk8ZI6+D6rI1+BdJDVsPJHwivTnMZIq10YHitn68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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