SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87c9c50590312e0f6a7ab55fe214bab0aa80e5a6aecda3c96b9ea21af864c5f1' 
  AND token = 'am6MB0EAowBiWsw+ae+04gD18h1vGdt78ZxAWpdVZ5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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