SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e15040df600bd8b4c52c6df826a6fc5aee60d2093969b4561bb9f381920a101' 
  AND token = 'WY1pJcv+u2kw4MN6fwdybm69kADZlLNVwNgnKmleKms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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