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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5b7e77b3755bc7ffddc3ac75bdde0578e6a413d8023993d3ce27f5d6e90b1a1' 
  AND token = 'o6b6VGdu9aozzCYzm9nGuWs2r+pph+SOzyz/pGo6lIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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