SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d86656f719fd170e3e601af934ed877f9f413f406013c4fae819091fc88a1e9' 
  AND token = 'Hhux+j5Kk26LM8Om5lO6w+5U8IdsjSid8VM6j+hjUbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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