SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75cb19c3fb8f7b07d8d1d94662173279dcbfff921b81cd2627848042f6eb1eac' 
  AND token = 'JhOVbL7iTYuIMIhcN5AY7YNgp6ZkJaeKv9wEVzegQq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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