SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2d52b4356758b8186afb8333c7864bf2820cc5d322b720dea6cb11ae559e7c1' 
  AND token = '4pJ9VJzPpJLcL6JoQxA7w4eDPzx7sMYnz89zq+09eN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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