SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '275adb27bf6438e232e13bab8c756d53df3eac86770f52932fa28530cf8f2ddf' 
  AND token = 'flmKZGNs+VovCJrfXyZWbUzhhIU1JX/WccPzQx8YjIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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