SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '318f769ee4866e8b03cd7220f2e334afd0121158a0dde6632e65afb250fc6c08' 
  AND token = 'hczIRiRY0phU7qIo+ncR3ZckU/tzBKPirlgCZUQuhZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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