SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb75581dd73268f6093ef18bdadda56b961abcdf26f5a143a172383f30c0df17' 
  AND token = 'gUYqdQByTXVRzCyGiSfYJCOW5/AI7BAnlSBzOZ66weo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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