SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c85cacea7c3d884e3a1e0d6fc2aeaa18204794630ac65f0e46b04689ae653e18' 
  AND token = '+3jNJBK/4kFs2c6UJj0gFuedK2sxCBiMHZCBkl+Uh4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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