SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb26aa3ceb80e4974937ccd6233d56deec986e51bed3f9f906f3e43df66e008d' 
  AND token = 'VBHFnb2oKmM6mgLBTlbOSNG5RBIQlHVY/vqpq0zXruU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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