SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b343c3f99eeebba05148a66678221bba3af157405c067f2e18ebc6751a2f79b9' 
  AND token = '6O+JexMqnaGMizeWigf0IR4L0i93+bYLgVxpUeooU/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00078

JSON explain

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