SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87d422ccada85b77a624e376394fc65801d6f6fec03a4f75c5f0030de0fd1a63' 
  AND token = 'D974dCge/aYANQuMZYktyHrP7jUVtiEDgOToa4RnXkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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