SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7710acb18cb8738136546efc479f579c1d867952280473d9d90a933da9eda835' 
  AND token = 'XshjocCvxZWks+a4lmSGBejhEXz7qgO3hflzoWQfOZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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