SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6716d3ca1166cd0de0d718e91d37e12a6920a248af1d18168d5c8c94c458c87d' 
  AND token = 'RU7uF1yaAixHdXroL/FBfcsYqrv63/h6gTCaR4zMFjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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