SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6df0e36507793b9e1aed4c98c7bd3294137ddb609e2c1742c5be323ee51bb6cd' 
  AND token = 'sZmyr6qwUtptHh9exhh14450eJ15JrMiz+NOruk1x9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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