SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8997c04092c2da852be1ad575cbb85fca334762629485f04e4cb4bf4686a571' 
  AND token = '5iv06kaYgNysfaSudr7rDhqJ8mQFHDzwRzxIRWeyhFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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