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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b59461368c7b436bda41365ab60a43ed90351163c47034c438df0ac9f6e2a3' 
  AND token = 'Whg3sZaEdBq28Jc9KKINZjTv2Y4AfbinQe3UAjrqGxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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