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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47c36e96062f1295e63ece52199a17f449b6d79bdc4263661499087bf490bc83' 
  AND token = 'b8lspTqblMEzGmq297zhek8pAcBDcDuSpaKD0EOgNzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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