SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b00f225717c22032f0fbc6553019e4a2d315af86b8bd3a9074bb2c2a59e7955' 
  AND token = 'U2jz32Zl4BS+n8Gu11OKPkRMmc3bqHxTxs1NNliWTJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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