SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7db227d751d5d49a08e97e76ff321135416e31dc7b12e8d5b0ba3a2eb4154512' 
  AND token = 'z0rzNv1jo9CxdDWCjjCwv3msUBdjkdyRh6bMvmVcFKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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