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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f63b775a75e1fce92b03f4509556c67c0f68b6feda99e9da96caafd874fb1621' 
  AND token = 'l6MliCBDauQN41SVQ43GY1lTxSRxCBI/VmN18jOtuOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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