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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ceaf87a40a6bf48001fdd255dfa077d46734bc8bbf2d4eb86cd5f7b700f404' 
  AND token = 'PkPZOuEMFoH/zIc0z28JrIt4SvZc9a3B1uyRA5Vg1PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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