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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd35c17302aba3f10ee19ef6ab62e3e09293d488b6c625b23952e6d9228f3c7f4' 
  AND token = '5YubEMVO/mEZRC4bGEKdmYBi4hLG8nAjA16hDFa/UsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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