SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9441da5c69226a49f431efa4d9fa0c50b8f276721565b7e07788c64f5c83139' 
  AND token = '4itQv1TzEq3vpLXJnaegRkezvhUY/5dnPEDN9wsdj0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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