SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '502eed23079fe36ca97c68cf009901755406eaf5e3e560d83807dbb63ef913d2' 
  AND token = '/7QQEDAFZNAwGjilMf0hkb3Q8F41wgU+hZGkSOF1rNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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