SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f8255965da6a2c36e4d96e13858bd2cd31fe2ccc91fc6bedd4d8dd02fbff20d' 
  AND token = '+bVo3ZnJwsk7doIufzwOYklKEqD/A670eLJIP0qg0E0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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