SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d7f560f540e47462ebb9d3a3ad169a8a11008cc176c3efea8325103336e495d' 
  AND token = '6IljFT3BnLAxtfFOOSfxtXZii93JuXuWqx6/ATKj3yY=' 
  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"
    }
  }
}