SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de6760ac2846c3e704f1bfede5e023bfcc6b02c0d1495cf4c805bedf0ea93f9c' 
  AND token = 'LZwKy2BQhZkgvilJTjoHBlG1zjnjQDra/ewK3mXTKyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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