SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8d15ca20df9392c64cb69595b23c74969be767071e911b879c645b7312c6780' 
  AND token = 'QtdHCTm6ZWUFKDGuxPt4CACjdDUX4sopyfXTB5/L0rI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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