SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '289be713138546d32c87a834d8b7f8c28deba658d2fde7d366874169bba81485' 
  AND token = 'w2gEDrjIpUCYJoDfZO2rUJIRlqHL2FzFpShyyWS5fU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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