SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e974abc166f57e6710bad25417aad91607503def9081b6fde5df571dd3418dfd' 
  AND token = 'usrboQkJpgYrQGmpr+K/qCZkfJdz5/bRIsm7b1XiAAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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