SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8ebcf308adcdf96cc11550f3ce938184ecf83921b20224fe22baaf144947023' 
  AND token = 'DtAsDV7gfDFTiP4wOwDWqvY6ebHvT8dnYB/N0QDIDHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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