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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f7e8eb6b940502f6e1fba5557bfe8484c5553a8faab1782ed1eb0eb1a0d2b04' 
  AND token = 'e1KRPL1nqRmqHk0VKpuXg+2/AegAUbKtRonxupPhRbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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