SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c949ec4acad954d690d6b812b79e467c6419071d1ae2fae56a626b1a6bad75d' 
  AND token = '0tMVXtnshFCTotlWTObsaZywqQ9EQvRsSfLuWMTZKhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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