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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a9abe139d1903cddcb57e9f34b4fde49aa0ed11ded1b4faf943f1f0044e9bcd' 
  AND token = 'e4fobhf0trtmXek8/P9nzPB3EUcBtdSeA0eYiw+qc3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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