SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78afa51b008ad6d196781f74e0ee50faea1f18ab855ae83768f64b3753e4822c' 
  AND token = 'U+4J2fnyVMqGZGF7hgh3tImHwHyHvJWLfXjK2H7kUrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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