SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87bbfc6384c5065dd140a89646938e934a3e3b016329182fbebdbf0f6e247366' 
  AND token = 'RC7u07jriXlzT5UU2bHuvWLyEsWzMZwNymAJT/RKzW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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