SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c656d3060562e077fdfbf4324e51f8107c1056c50b75351cb0cecd29b659af94' 
  AND token = 'VKrsThWEsDtmJZso3+PGm7gwa4cGAF1XBRiawvij7gc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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