SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3168696b20358bcde771e5ef4366b6a0904bf2f1c7fa701a4d2f9d8560f2183' 
  AND token = 'eUkxF9NasjuquP/THBrHRnULspteKmspQX/pg1iL4Vs=' 
  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"
    }
  }
}