SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9e79aa4b4145424463679c632e7a2af9d34e851e7b24e91e2012687dafddcbc' 
  AND token = 'U9z0tVYQYvELa1wMFWmLB5IyZMuAM6UhWgmsyrUd+/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}