SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6a86de21323efbeacd880c6e8ea25ae1167902db7a60c11f9ace839da8235d6' 
  AND token = 'jQhWJm/miDWCuKXYc+Er8qWAFbDIr88T/mC2yphfA40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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