SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a83b98aa1731df3406d84c52baef73db73339dec7dc1f1cd89c9d1682be162fb' 
  AND token = '1JDm6KMFTe2PJwMLNKPzPoIsxsvKvnIzcNecnnZT6Ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}