SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d7c6fc524cf857a81d138259708cd1d7b169244a888f1890a784f4b38daa921' 
  AND token = 'pmPEqJHn+gK6VI6KpTQN9U9ZzN47mCMypP1/QdJ2zBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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