SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da7d53f3503e98d08bbe6336f5dabce50b84a09b1da956c7648518db0fdeed60' 
  AND token = 'M8+iAeKdnJAAcH1DPVUZ6qygtZSwO3fjl0YjgCxT6jE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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