SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb50a813e1075071493be44878058ef09262ac69708ddce81ef62dcb5df9f4fe' 
  AND token = 'rUbOWLpz1c3zntBsg6Gn9phXDmh8BiSIBgeC2rsxB6s=' 
  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"
    }
  }
}