SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86d3c35101672b4d5448d9342bb6ecc2edd311aafe8c0a6f26556d60dab045be' 
  AND token = 'ueFHCDJ8VZJ4G2ZnBxGi2sfAwd9zJpkb9DGQfg8ZzCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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