SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '191f0d66acb0eb33284489810a3fa404c949e3f475bc89d79e3bc81563c7a8aa' 
  AND token = 'B/RsWFWbSsmEM6RWJunJHorwzR2Ch56hDNsaXZphsRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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