SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '136fefeb7b641cd6b57b22475a0aa569683f83a1355f337eb4dba4d7786bad55' 
  AND token = 'KFtFLOrg6L2hq5XrYOuGsxGTWtzXmosZl81hJnaQJC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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