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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8df78a287e6dd03a757c6610d27616ba7c907abde017dd140fea660d787e8f59' 
  AND token = '7tQth0sFZXWgk3Q3/+D1elFdTsMz/+5vEVou+ivOLbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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