SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c57b58e47f21db92b403cfe3fbd6493f13423f2aa583f9a5d2deace1e75eb3cb' 
  AND token = 'ffXnv4i8Wl9zmBLkZevmJ5U8miP4TybDT0ikAFQetR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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