SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f9fc396deed26ae52a081d4fc183b58a6d69a0c77965b311655c94531a41dec' 
  AND token = '/kaSVXIMysE7bBu2XwPKnuUG+Z97Jbgy5eW4KOhAlMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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