SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3399a8b9d365b0fff462c5662725b350e53c7b71ee867bba58774ed10484221' 
  AND token = 'yrf+QoBC2iFVA+FHXb2xhcN/g5+2TZWX9qsO8QCimKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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