SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d2bf83404945ab882e788aa8794b35c6a6bf2d63dd9f1b1ba3f0abaa06150f' 
  AND token = 'hUURaBz6e+vE15JaEBqj+bh8LCZNIDQXCAgmgDdhG4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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