SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c2c0a55074735771073dbf352b68affae0b27befd88405a6deef113307f8687' 
  AND token = 'meYFQxI0bZBOPHVEBOAZHy33PbI35JMnWeTPmdWxRc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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