SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fbedd78535a376c9557b5c185fabf505097fd6eb6b130f69d1671281cf9119d' 
  AND token = 'lVMSDdGthPBlAbM4+3dZKjwQQISUa1YjHSydmkMcDCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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