SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8973c577d3146186ed1a2a86049d87278afe1a94bff499a45e0befa934d408a' 
  AND token = 'Er8r69WsWVs80nK7ez4R7gIHYn+Nw2tWMy31EBvTzSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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