SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c03c577579289cd07091d8bfb8904d914af26ba385f4a5e9f76383e844dbf877' 
  AND token = '+6ZUmuwCq61GPt/LdqLcjvMXcD25wfWYPRc9s4xmRf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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