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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dde8a3bd163460e1d7a73380160c8597f2cdc7d9e73a7577d99a61cd6c62c14' 
  AND token = 'CT3EgVSZnGPo9Wi9Q3odZIDOdoWWWoYY+CNKxKQdMuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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