SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c79464876f4031b99d26ad6b5663059e28ba9813c547117c3756e299ad993c8' 
  AND token = '/qSjJobYAeLZiBFbwjyz2JAEuXDP2RpvRn2WDvVtuh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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