SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fd7332f7faf0bf4484302909cf84a3209b2b60c67cdee339837cee560813b8c' 
  AND token = 'UCukHOY2nSz3oc9zfXhOClDUoRuXOqi78ipewRAd590=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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