SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b15760a069e86638aa929b2c1b195c7a6c5c70df71a9926f889c1579cfeaeb1d' 
  AND token = '6U3c1YFO4fJaT+DGVpKbGA0EbkKeSXOLdE+A3eg4XLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}