SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86829cd47018eea94f2dede59c06de16a921e8d94f57ee89f75be9432bc8accb' 
  AND token = 'F5hNXOdfZiPbfStgWGH8vqsPLgVlyKxs0STsadYy+gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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