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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cbefbbcb5fa3eac324c809555272e919d6b2b837ef6cc662f5ed229ff365c49' 
  AND token = 'UyaBsdkFs/AD5RL3BYo+krJa+Vhq1q/i4WPFRQXTzbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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