SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a5e4c5260b3103ae83cb0a0b904b21c9235a073bb25df5f0a78c163fa874745' 
  AND token = 'AUEcHUrcBlSB3MIfEE916AEPHDux7xv6pCfNgrdrNmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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