SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0421c5175e9598054a124feea1e168db0ae6cf55f87121b826e3290166a1403d' 
  AND token = 'Khcc4cF/BG4awLmxdocyi6gA9If0fYudufiyYv81OFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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