SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c815284f8824ddef0bed6562a74278db0f8420263c089c2bce326f2f14849121' 
  AND token = 'OQOiDeYbT5AVpSE1AMWHe4b7LxMWf8IGOVA6IbrstS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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