SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc5135db6c9524438a20655948019f147f6fec8c588d7866c7d02854447599a3' 
  AND token = '7h0z+bndIEJFyxOsjGkGuZSML0fNh6O5Kl1cks7Ut38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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