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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc1624ee3c4503ba4438c5d9f79bd655049dd7e5ddebbe3cb881cfe4dd0356ae' 
  AND token = 'ia/cvPxUiQ2aQyZOT6Cr2lmIL0z1sUGhoZw+wKIDzbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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